Plastic Chef Neelix
"What kind of cook thinks that increased heat equals less cooking time? A bad one!" Chuck Sonnenburg.
This page is dedicated to the general cooking fail that is Neelix.
Neelix does not respect the tastes of others
It is something that that many good chefs are known for is to tinker with recipes in order to improve upon them or to overcome a missing ingredient that isn't available. Neelix does not do this well and in fact he finds ways to force his own versions of dishes on those he is serving even when every part of the original recipe is available.  He seems to think that no matter what he is told that his special additions are always an improvement and is flummoxed at the very idea that someone could dislike his new version of the dish. This includes the additions of spices that he is constantly told that the patrons can't stand. This goes so far as to insist that when food is smuggled out of his kitchen because someone wanted to make a dish their way rather then his required some type of punishment.  It's understandable on a minor level that he would try to convince them that using locally available supplies are a worthwhile effort but if something does not please the pallet of a patron you shouldn't force it onto them. No this is not the same as convincing children to eat their vegetables, as the items he insists on adding are only flavor enhancers not items of any real nutritional value.
Neelix always cooks his food on high
It's somewhat understandable in the context of filming something cooking on screen to use an obviously visible flame but what we see Neelix doing goes well beyond that. In every cooking operation we see Neelix doing he is always doing so with the flames so high that fire licks up to sometimes half the height of the sides of the stock pot he is preparing sauce in. Something that any good cook will tell you is, those kinds of heat levels are only useful in a vary narrow number of applications, wok based cooking is a good example. This goes to explain why we see Neelix overcooking or even outright burning food on multiple occasions. 
Ignoring that it then brings up the massive waste of resources represented by his constant cooking at such high levels. We are constantly being told that power reserves are precious to then see Neelix constantly overusing energy to cook the food that is suppose to be helping. No matter how the technobabble is explained to us it doesn't change one detail that the energy is being used very inefficiently to do tasks where not even close to those levels is required.
Neelix thinks that higher temperatures equals faster cooking times.
This next section is partially related to the above point but not entirely as it showcases a different cooking related issue. In the episode Flashback, a technobable material in a nebula is discovered that Neelix says they could inject into his cooking array and cook his meals in half the time. Because of the level of techno gibberish in this scene it's isn't right away obvious the assumption that Neelix is making here. To make it clear doubling the combustion rate of his burner is suppose to half the rate his cooking will take to finish. This leads into something that is often called "Oven Logic" and is failing made by many amateur cooks. Doubling the power of your burner does not half the cooking time, or any other linear expectation, because of the complex chemical interactions that takes place whenever you cook anything.
Neelix lacks even basic sauce making skills.
Neelix is seen in the episode, Learning Curve, to be making macaroni and cheese where his solution for making a cheese-based sauce was to take a chunk of solid cheese and just toss it into a pot filled with macaroni and leave it at that. While with some soft young cheeses this is possible, even with those kind of cheeses an experience cook will melt the cheese into a separate saucepan and integrate it into a sauce then add that to the pasta. Also this is another place where his inability to ever turn down his burners will generally spell disaster as the pasta would be very over cooked before the cheese will become anything close to a stable sauce.
His high burners also means that when he is making a large amount of a spaghetti-type sauce he is required to make use of constant tending of the stew-pot that the sauce is cooking in in order to prevent it from burning. This is something that does not tend to produce a tomato sauce that will have much of anything that could be called good flavor or texture. This may be the reason Tom Paris expressed annoyance at the quality of his Spaghetti. 
Neelix does not seem to understand basic food safety principles
Once again we are forced to look to the disaster that was Learning Curve. Neelix has made a batch of homemade cheese and the manner he is storing this cheese is in a bell jar-like container on the counter in his kitchen. While there are a few cheeses that can be stored in a room temperature state(none of which Neelix had the resources to make) without much worry most experienced cooks will still store them in a refrigerated environment as that is just one extra precaution against food poisoning. The danger-zone is a very real concern and as evidenced by Neelix managing to infect the ship itself with his cheese just begs the bigger question of how many food poisoning cases was the Doctor dealing with that they just didn't care to show us.
Neelix solution for cleaning greens for use in a salad was to shake them off and set them on the counter. 
Neelix is not a good example for anyone on how to operate a kitchen in any sense of the word. It is a sad reality that a cook book that has been produced featuring Neelix on the cover. I'd rather see the book with Sisko on the cover as at least he seems to know what he is doing. The sad part of this book is the recipes that had to have been created by competent chefs that are now associated with this insult to culinary arts that is Neelix.